Combination axial-flow fan

ABSTRACT

A high-performance low-noise combination axial-flow fan includes a fan hub that has a center connection portion for the connection of a fan motor shaft and a plurality of mounting grooves equiangularly spaced around the periphery, and fan blades each having a wedge block disposed at the inner end for insertion into one mounting groove to secure the respective fan blade to the fan hub so that the fan blades are radially fastened to the fan hub and no gap is seen between each two adjacent fan blades when viewed from the front side.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a fan and more particularly, to acombination axial-flow fan for use in a computer or electronic productfor forced air convection cooling.

(b) Description of the Prior Art

Regular cooler modules are designed for use in electronic andphotoelectric products to expel waste heat. A typical conventionalcooler module is comprised of a passive heat dissipation device and anactive heat dissipation device. A passive heat dissipation device can bea heat sink extruded from copper or aluminum and having multipleradiation fins. An active heat dissipation device can be an axial-flowfan that forces surrounding air to cause convection, thereby loweringthe surrounding temperature. A typical conventional axial-flow fancomprises a fan hub 10 and multiple blades 20 integrated into andextending around the periphery of the fan hub 10 (see FIG. 6). By meansof controlling a motor to rotate the fan hub 10, the blades 20 produce awind pressure, achieving force-air cooling Because the parameters of 3Dcamber, angle, number and radius of the fan blades determine the windpressure, pressure amount and noise levels, it is the optimum designwhere there is no gap structure seen in the fan blades when viewed fromthe front side, i.e., the front edge of one fan blade blocks the rearedge of another adjacent fan blade.

However, this design is not applicable due to technical problems inmolding technology. A partial fan blade overlapping arrangement willresult in a mold stripping problem after injection molding. Therefore,there is a gap d' between each two adjacent fan blades 20 (see FIG. 6),allowing removal of the molded fan from the mold. The presence of thisgap d' is one of the major reasons of the production of wind noise. Italso tends to cause an insufficient wind pressure problem, whichpresents difficulties in satisfying heat dissipation requirements ofmodern electronic devices.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances inview. It is therefore one object of the present invention to provide acombination axial-flow fan, which has the fan hub and the fan bladesseparately made and then assembled together so that the front edge ofone fan blade is suspended above the rear edge of another fan blade, nogap is seen between each two adjacent fan blades when viewed from thefront side, and has high wind pressure, high wind capacity and low noiselevel characteristics.

To achieve this and other objects of the present invention, thecombination axial-flow fan comprises a fan hub and a set of fan blades.The fan hub and the fan blades are separately made and then assembledtogether. The fan hub comprises a center connection portion for theconnection of a fan motor shaft, and a plurality of mounting groovesequiangularly spaced around the periphery. Each fan blade comprises awedge block disposed at the inner end. The wedge block can be insertedthrough the rear open side of one mounting groove to secure therespective fan blade to the periphery of the fan hub. The mountinggrooves can be dovetail grooves. In this application, the mountinggrooves are dovetail grooves, and the wedge block of each fan blade is adovetail block fitting the dovetail configuration of the mountinggrooves.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a combination axial-flow fan according tothe present invention.

FIG. 2 is an assembly view of the combination axial-flow fan accordingto the present invention.

FIG. 3 is a sectional view of a part of the present invention, showingthe dovetail mounting grooves of the fan hub.

FIG. 4 is a sectional elevation of the combination axial-flow fanaccording to the present invention.

FIG. 5 is a front view of the combination axial-flow fan according tothe present invention.

FIG. 6 is a schematic front view of an axial-flow fan according to theprior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, a combination axial-flow fan inaccordance with the present invention comprises a fan hub 1 and aplurality of fan blades 2. The fan hub 1 and the fan blades 2 areseparately molded from plastics by means of injection molding, and thenassembled together for use as an active heat dissipation device for thecooling of an electronic product.

Referring to FIGS. 1 and 2 again, the fan hub 1 may be made in any of avariety of shapes. According to the present preferred embodiment, thefan hub 1 is shaped like a round cap, having a center connection portion11 at the center for the connection of the shaft of a fan motor (notshown), and a plurality of mounting grooves 12 equiangularly spacedaround the periphery. The mounting grooves 12 can be dovetail groovesextending axially towards the rear side 13 of the fan hub 1 so that eachmounting groove 12 has an open end 121 at the rear side 13 of the fanhub 1.

Referring to FIGS. 1 and 2 again, the fan blades 2 are identical inshape, each having a front edge 21, a rear edge 22, an outer edge 23 andan inner edge 24. There are no particular limitations on the 3D camberand geometric shape of the fan blades 2. The 3D camber and geometricshape of the fan blades 2 can be modified to achieve optimum performancesubject to aerodynamics. Each fan blade 2 further has a wedge block 25.The wedge block 25 is a dovetail block fitting the circular shape of theperiphery of the fan hub 1 for engagement into one mounting groove 12 ofthe fan hub 1. By means of engaging the wedge blocks 25 of the fanblades 2 into the mounting grooves 12 of the fan hub 1, the fan blades 2are fastened to the fan hub 1 and radially equiangularly spaced aroundthe periphery of the fan hub 1.

After installation, as shown in FIG. 2, the fan blades 2 are radiallydisposed around the fan hub 1 and equiangularly spaced from one another.Thereafter, the center connection portion 11 of the fan hub 1 isfastened to the shaft of a fan motor (not shown) and then the assemblyof the fan hub 1 and fan blades 2 is mounted with the fan motor in arack, constituting an electric fan for use in a cooler module forcooling a computer or any of a variety other electronic products.

Because the fan hub 1 and the fan blades 2 are separately molded fromplastics and then assembled together, fan blades having different 3Dcamber and geometric shape features can be selectively used with onesame fan hub to constitute different combination axial-flow fans fordifferent applications to satisfy different cooling requirements,thereby lowering the mold cost. More particularly, as shown in FIGS. 4and 5, because the fan blades 2 and the fan hub 1 are separately madeand then assembled together, it is practical to constitute ahigh-performance axial-flow fan having low noise level, i.e., the frontedge 21 of one fan blade 2 is suspending above the rear edge 22 ofanother adjacent fan blade 2 so that no gap is seen between each twoadjacent fan blades 2 when the axial-flow fan is viewed from the frontside (see FIG. 5), however the desired wind tunnel D is still maintainedin between each two adjacent fan blades 2 (see FIG. 4). This fanstructure is not achievable by conventional fan designs. By means of theapplication of the present invention, this fan structure is easilyattainable.

Although a particular embodiment of the invention has been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

1. A combination axial-flow fan, comprising: a fan hub, said fan hub comprising a center connection portion for the connection of a fan motor shaft and a plurality of mounting grooves equiangularly spaced around the periphery thereof, each said mounting groove having an open side disposed at a rear side of said fan hub; and a plurality of fan blades, each said fan blade comprising a wedge block disposed at an inner end thereof insertable through the open side of one said mounting groove to secure the respective fan blade to said fan hub.
 2. The combination axial-flow fan as claimed in claim 1, wherein each said mounting groove is a dovetail groove.
 3. The combination axial-flow fan as claimed in claim 2, wherein the wedge block of each said fan blade is a dovetail block. 